Twitter and Facebook may be blocked in Iran but that has not stopped millions of defiant Iranians finding a way to access them. Now they appear to have been joined by the country's supreme leader, Ayatollah Ali Khamenei.

Having already dabbled in tweeting and sharing photos on Instagram, the 73-year-old ayatollah, who purports to be God's representative on Earth, has now embraced Facebook.

The news came from Khamenei's Twitter account, believed to be run by his office, which promoted his recently launched Facebook page by posting a link. Within just a few days, it has received more than 10,000 "likes" and attracted a great deal of attention at home and abroad.

Khamenei's official website has not yet confirmed the existence of the page, but Baztab, a conservative news website, said the account was run by his office.

Not long ago, Iranian authorities deemed such websites decadent, instances of the so-called "western soft war" conspired by the likes of the "Zionists". But as more and more people join them, they risk being left behind. Khamenei's online activities could now pave the way for other officials who may still consider it taboo to use online social tools.

The latest post on the supreme leader's Facebook page is a YouTube video that features Hassan Nasrallah, the leader of the Lebanese militant group Hezbollah, and Khamenei, each separately commenting on the concept of the new Mlddle East.

"There is no doubt that a new Middle East will be formed," Khamenei is shown telling a group of Iranian officials in February 2010 on the eve of the Arab spring. "This Middle East will be the Islamic Middle East." Since the pro-democracy movements in the Arab world, Khamenei has labelled them the Islamic awakening, likening them to Iran's Islamic revolution in 1979.

Another post is an old photo of Khamenei, showing him with Ayatollah Rouhollah Khomeini, the founder of the Islamic republic. The picture has been modified by Instagram to highlight the faces of the two men.

Many users have posted comments to voice praise or express opposition to the Facebook page. "Gratitudes to my compassionate leader," said one user. "Death to dictator," said another. Comments are moderated and some deleted afterwards.

A US state department spokeswoman, Victoria Nuland, said on Monday that Washington would carefully observe the Facebook page and joked it would keep an eye on how many "likes" Khamenei received.

Access to more than 5m websites is blocked in Iran. People who try to visit blocked addresses are redirected to a web page that reads: "Access to the website is denied according to [Iran's] computer crimes regulations."

However, many Iranians access blocked addresses with help from proxy servers or virtual private network (VPN) services.

Commenting on Khamenei's page, some users jokingly asked what kind of VPN services the supreme leader was using to access Facebook.

"Can you ask them to lift the filtering of Facebook?" pleaded one user in a comment.

Iran's filtering machine is very complex and sometimes sensitive to certain words. On one occasion, Khamenei's own fatwa became a victim of his regime's filtering machine.

Khamenei's office has already been active on Twitter, posting tweets in Farsi, English and Arabic. Around 3,200 tweets have been posted so far and some 7,500 people follow him. World dignitaries who might follow Khamenei and expect to be followed back may, however, be disappointed as the supreme leader follows no one.

Khamenei's move might be interpreted by many of his officials as a green light to embrace the internet, especially in the months before the country's presidential elections in 2013. Mahmoud Ahmadinejad will step down as president in June. He would not be able to run for a third time under the constitution.

At the time of Iran's last presidential elections in 2009, online social tools became a phenomenon in the country with many activists taking to Facebook and Twitter to campaign for their favourite candidate.

After the vote's results, which prompted street demonstrations amid allegations of fraud, people also went online to organise protests, and citizen journalism became a new concept. The authorities, too, used the internet to identify and arrest dissents. Many people were arrested for their online activism on Facebook and Twitter.

The role of social networking websites in Iran's 2009 disputed elections has since been debated among analysts with some saying that its effect had been exaggerated at the time but many believe that it later inspired people in the Arab world.

After 2009, Iranian officials became sensitive towards online services, going as far as labelling Google a spying tool. As late as April, a military parade in the central city of Isfahan, featured vehicles carrying billboards labelled "damages of the Facebook internet site".

Recently, an Iranian blogger, Sattar Beheshti, lost his life while in custody after being arrested by Iran's cyberpolice for his opposition activism on Facebook.